LINK TO ORIGINAL POST:
https://www.fordbarn.com/forum/showthread.php?t=278347
This part is going to cover the preparation of the gearbox case (7006 in the drawings). The 1949-50 Mercury transmission case was very similar to the earlier types (32-39 toploaders and 40-48 sideloaders) in that they have the large round bell shape at the interface to the engine. The casting also carries the clutch release shaft, with the release bearing and hub.
Now that the casting has been cleaned and painted, we do a quick check and clean of all the bolt hole threads. We use old worn out taps to run through each bolt hole. This provides a final cleaning to remove any small particles of dirt or rust that survived the oven bake process. We want these threads to be clean for the eventual sealing thread locking compound that will be used on the retainer bolts.
This type gearbox case will have two bushings to support the clutch release shaft that passes through the gearbox. Most of the early Ford transmission cases used the thin wall bushings (approximately .030" wall thickness). As Ford moved through the 1940's they started to bore out the cases for a thicker bushing (about .060" wall thickness). All of the 49-50 Mercury cases use the thicker bushing. These do not come predrilled for the grease zerk fitting passage, so we have to score the center and drill them for this opening. The steel shell of the bushing is rolled so there is a very fine seam...drill the hole opposite the seam. I used a 1/4" bit but you can use up to 3/8" diameter. Clean off the chips and remove any burrs before installing.
Lubricate the bores to accept the new bushings. Place the bushing at the opening, lining up the grease hole with the zerk fitting hole in the case. We use a simple bushing driver to tap the bushings into place. They are typically pretty tight when installed.
The overdrive adapter casting will have the solenoid oil seal installed. This fits into the small recess of the face that holds the solenoid itself. A bit of sealant is used here to help keep the seal in place.